1. Field of the Invention
The present invention relates to an apparatus for charging a green tire into a tire vulcanizing machine while centering the former with respect to the latter.
2. Description of the Prior Art
The inventors of this invention under application previously invented a method and an apparatus for forcibly centering and inserting upper and lower bead portions of a green tire with respect to and into upper and lower bead rings of a metal mold, and a patent application was filed at the Japanese Patent Office as Japanese Patent Application No. 01-019869 (1989). Also, in the specification of U.S. Pat. No. 4,444,715 is disclosed the technique of feeding pressurized gas into a green tire for the purpose of preventing an upper bead portion of a green tire from slipping out and falling due to the weight of the green tire.
Since crude rubber has the nature that it becomes fluidness if heat is applied thereto, depending upon the time elapsed before a predetermined pressure is attained after shaping steam was injected into a green tire carried in and mounted to a metal mold, sometimes an upper bead portion of the green tire inserted into an upper bead ring of the metal mold would slip out due to the weight of the green tire. Moreover, since upper and lower bead portions of a green tire carried in a tire vulcanizing machine are more or less deformed and a concentricity, a degree of parallelism and the like are low, depending upon a degree of deformation, sometimes a bead portion of a green tire on the side which is inserted first into a bead ring would slip out due to reaction forces for reforming these deformations.
As a counter-measure against the above-mentioned problems in the prior art, in the specification of U.S. Pat. No. 4,444,715 is proposed a method for preventing an upper bead portion of a green tire from slipping out of an upper bead ring by injecting pressurized fluid into a green tire and causing the fluid pressure to support the weight of the green tire. However, this proposed method still involves problems such that a large amount of pressurized fluid is consumed due to the presence of irregularities such as joints of members on the surfaces of bead portions of a tire, and depending upon a degree of deformation of a green tire, it would be difficult even to raise an inner pressure of a green tire.
Although it would be conceived by anybody that if any mechanism for mechanically preventing bead portions of a green tire from slipping out is assembled, the above mentioned problems will be resolved. However, generally a chuck mechanism or the like (commonly called "upper center mechanism") is assembled inside of the upper bead ring, while a bladder operation mechanism (commonly called "lower center mechanism") is assembled inside of the lower bead ring. Therefore, because of spatial restriction, the above-mentioned method has not been realized.